You can't have a Nurgle genestealer cult without Nurgle. I just finished striping and repainting my Great Unclean One for my genestealer cult. I was going to use him for 3rd ed fantasy, but its really difficult to take one in a chaos army, except for a daemon army, so I decided to use him for Rogue Trader instead.
Nurgle's Trinity. The Great, Great Grandfather, Great, Great Grandson and the Unholy Daemon.